"I Buckle Myself"

I was picking up the bedroom to get ready for the cleaning lady and Kevin was in the bathroom getting ready for work and all of a sudden from the back of our closet we heard, "I buckle myself!" So we both went back there and we couldn't find him, but we could hear him. "I buckle myself" over and over. We walked around our built-ins to the other side of the closet and found this proud little boy grinning from ear to ear. "I BUCKLE MYSELF!" Indeed, he did!